不同加工条件对茶叶超微粉碎效果的影响

应用小型气流式粉碎机制备超微茶粉,激光衍射粒度分析仪测定其粒度分布,对工质压力、分选频率、粉碎次数、进料速度四因素分别进行实验。结果表明,随工质压力的增加超微粉粒径减小,工质压力大于0.7MPa时,粒径的减小趋缓;进料速度过大、过小都不利于粉碎;随分选频率的增加超微粉粒径减小,应用到食品方面时25 Hz即可达到要求;随粉碎次数的增加超微粉粒径变化不大,只是分布更集中。最佳实验条件为：工质压力0.7 MPa,分选频率25 Hz,粉碎1次。在此条件下得到超微茶粉的D50（中位径）和D90（积分分布90%时的粒径）分别为12.41μm和40.21μm,且粒度分布集中。

Effect of Different Processing Conditions on Tea Ultrafine Pulverizing

Ultrafine tea powder was prepared by Mini-Airflow Pulverizer System under different conditions. Also its particle size distribution was tested by Laser Diffraction Particle Size Analyzer. Combined single factor test, main factors such as work quality pressure, sorting frequency, grinding times and feed-in speed that affected the particle size distribution were discussed. The results showed that ultrafine tea powder diameter decreased with the increase of work quality pressure. When work quali- ty pressure was larger than 0.7 MPa, diameter decreased slowly. Higher or lower feed-in speed was unfavorable to particle size distribution. Diameter gradually decreased with the increase of sorting frequency. 25 Hz sorting frequency could meet the diameter requirement when used in food. With the increase of grinding times the diameter changed unobviously, but particle size distributed more centralized. Therefore, the optimum experiment parameters were： work quality pressure 0. 7 MPa, sorting frequency 25 Hz and grinding one time. D50 （median diameter）and Dg0 （integral distribution 90% diameter） were 12.41 μm and 40.21 μm respectively, also the particle size distribution was centralized.